Cochise College          Photos of Minerals

                          Geology Home Page                

                          Roger Weller, geology instructor

                          wellerr@cochise.edu
                                  copyright 2006-R.Weller
 

Mineral Information on:
sillimanite

Chemical Group:    silicate

Chemical Formula:   
Al2SiO5

Color:  light brown, grayish brown, pale gray, grayish green, pale olive green

Transparency:  transparent to translucent                                                                         

Streak: uncolored                  Fracture:  uneven

 

Hardness:  6 to 7                Specific Gravity:  3.23 to 3.24                 

Cleavage:  (010) perfect

 

Crystal Forms: Monoclinic system
     Crystal are long and thin, tending to fibrous

Mineral Associations:  corundum, cordierite, andalusite

Identifying Characteristics:

Uses:

Occurrences:  Connecticut, New York, North Carolina

Toxicity:      when-swallowed- low         when inhaled- high

Additional Information: